The eutopic endometrium of women with endometriosis, compared with disease-free individuals, contains certain molecular alterations, including the differential expression of microRNA (miRNA). The aim of the study was to compare the expression of the most relevant miRNAs in the eutopic endometrium of women with and without ovarian endometriosis.

Methods: A total of 46 regularly menstruating patients, 21 patients with ovarian endometriosis and 25 controls, underwent surgery in the proliferative phase of the cycle.

The eutopic endometrium was collected through aspirating biopsy prior to laparoscopy. Only patients with advanced (stage III and IV) histopathologically confirmed ovarian endometriosis were included.

TaqMan MicroRNA Array Cards were applied to examine the expression of 667 human miRNAs in 10 patients with endometriosis and 10 controls. Custom-made, low-density real-time PCR arrays were used to confirm the expression of 15 selected molecules in 21 endometriosis patients and 25 disease-free individuals.

Results: Of 667 miRNAs, 2 were highly likely to be upregulated and 13 were downregulated in the eutopic endometrium of patients with endometriosis compared with the controls.

Validation using real-time PCR showed that hsa-miR-483-5p (p = 0.012) and hsa-miR-629* (p = 0.02) are significantly downregulated in patients with endometriosis.

Conclusions: Changes in the expression of select miRNAs might lead to or be a consequence of an early defect in the physiological activity of the proliferative endometrium, ultimately resulting in the overgrowth of this tissue outside the uterus.